/in/foo.c:5:7: error: variably modified 'x' at file scope
 int n,x[max],y[max],s[max];
       ^
/in/foo.c:5:14: error: variably modified 'y' at file scope
 int n,x[max],y[max],s[max];
              ^
/in/foo.c:5:21: error: variably modified 's' at file scope
 int n,x[max],y[max],s[max];
                     ^
/in/foo.c:7:1: error: unknown type name 'bool'
 bool check(long double v){
 ^~~~
/in/foo.c: In function 'check':
/in/foo.c:12:12: error: 'false' undeclared (first use in this function)
     return false;
            ^~~~~
/in/foo.c:12:12: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:19:10: error: 'true' undeclared (first use in this function)
   return true;
          ^~~~
/in/foo.c:20:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^